After experiencing issues of non-compliance, the Steamship Authority said it was tightening up its own ship with regard to mask-wearing on Wednesday, releasing enforcement guidance for employees that include leaving mask-less passengers behind and contacting law enforcement.

The SSA instituted a mandatory mask policy in late April, just days before Gov. Charlie Baker’s statewide rule requiring masks in public, including public transit. The order requires passengers to wear masks while boarding SSA buses and vessels and on interior decks. Socially-distant passengers are not required to wear masks outdoors.

But in a press release Wednesday, the boat line officials said it had experienced difficulty enforcing the rule and issued specific guidelines for employees.

“I know that all of you have experienced difficulty at times with customers who decline to comply,” said a memorandum to that went out to employees from director of shoreside operations, Alison Fletcher and was attached to the press release.

“Please know you have the full support of myself and general manager Bob Davis in this regard.”

The guidelines include offering a disposable mask to customers traveling without a cloth face covering for bus trips, repeated announcements during travel, reiterating that customers cannot board vessels or buses without masks, leaving any belligerent customers behind, and, if the situation merits, involving local law enforcement or the state trooper stationed on the boat.

Buses cannot leave the station if a passenger gets on without a mask, the memorandum notes, and boats are now instructed to continue loading and to leave passengers in port if they do not wear a mask.

SSA spokesman Sean Driscoll said the enforcement guidelines came about after multiple instances of non-compliance on boats and buses, many not unique to the boat line.

“We did have an incident on a bus recently. That really has been the biggest problem,” Mr. Driscoll said. “We have continuous issues on the vessels with customers acting like they are in ninth grade, and taking off their mask when the teacher walks away, and then putting it back on when the teacher comes back around.”

There are no official policy changes with the enforcement guidelines, Mr. Driscoll said.

“There’s not really a difference in the policy as far as what’s required, it’s more additional guidance to our staff on how to proceed if they encounter a passenger who has a different point of view,” Mr. Driscoll said. “We just wanted to make clear for employees that we would back them up.”